tools/genboardscfg.py: check if the boards.cfg is up to date

It looks silly to regenerate the boards.cfg even when it is
already up to date.

The tool should exit with doing nothing if the boards.cfg is newer
than any of defconfig, Kconfig and MAINTAINERS files.

Specify -f (--force) option to get the boards.cfg regenerated
regardless its time stamp.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>

tools/genboardscfg.py

@@ -85,6 +85,52 @@ def get_make_cmd():
         sys.exit('GNU Make not found')
     return ret[0].rstrip()
 
+def output_is_new():
+    """Check if the boards.cfg file is up to date.
+
+    Returns:
+      True if the boards.cfg file exists and is newer than any of
+      *_defconfig, MAINTAINERS and Kconfig*.  False otherwise.
+    """
+    try:
+        ctime = os.path.getctime(BOARD_FILE)
+    except OSError as exception:
+        if exception.errno == errno.ENOENT:
+            # return False on 'No such file or directory' error
+            return False
+        else:
+            raise
+
+    for (dirpath, dirnames, filenames) in os.walk(CONFIG_DIR):
+        for filename in fnmatch.filter(filenames, '*_defconfig'):
+            if fnmatch.fnmatch(filename, '.*'):
+                continue
+            filepath = os.path.join(dirpath, filename)
+            if ctime < os.path.getctime(filepath):
+                return False
+
+    for (dirpath, dirnames, filenames) in os.walk('.'):
+        for filename in filenames:
+            if (fnmatch.fnmatch(filename, '*~') or
+                not fnmatch.fnmatch(filename, 'Kconfig*') and
+                not filename == 'MAINTAINERS'):
+                continue
+            filepath = os.path.join(dirpath, filename)
+            if ctime < os.path.getctime(filepath):
+                return False
+
+    # Detect a board that has been removed since the current boards.cfg
+    # was generated
+    with open(BOARD_FILE) as f:
+        for line in f:
+            if line[0] == '#' or line == '\n':
+                continue
+            defconfig = line.split()[6] + '_defconfig'
+            if not os.path.exists(os.path.join(CONFIG_DIR, defconfig)):
+                return False
+
+    return True
+
 ### classes ###
 class MaintainersDatabase:
 
@@ -503,7 +549,7 @@ class BoardsFileGenerator:
 
         self.in_progress = False
 
-def gen_boards_cfg(jobs):
+def gen_boards_cfg(jobs=1, force=False):
     """Generate boards.cfg file.
 
     The incomplete boards.cfg is deleted if an error (including
@@ -513,6 +559,10 @@ def gen_boards_cfg(jobs):
       jobs: The number of jobs to run simultaneously
     """
     check_top_directory()
+    if not force and output_is_new():
+        print "%s is up to date. Nothing to do." % BOARD_FILE
+        sys.exit(0)
+
     generator = BoardsFileGenerator()
     generator.generate(jobs)
 
@@ -521,7 +571,10 @@ def main():
     # Add options here
     parser.add_option('-j', '--jobs',
                       help='the number of jobs to run simultaneously')
+    parser.add_option('-f', '--force', action="store_true", default=False,
+                      help='regenerate the output even if it is new')
     (options, args) = parser.parse_args()
+
     if options.jobs:
         try:
             jobs = int(options.jobs)
@@ -534,7 +587,8 @@ def main():
         except (OSError, ValueError):
             print 'info: failed to get the number of CPUs. Set jobs to 1'
             jobs = 1
-    gen_boards_cfg(jobs)
+
+    gen_boards_cfg(jobs, force=options.force)
 
 if __name__ == '__main__':
     main()